Method and device for image contrast enhancement

A device for image contrast enhancement, comprising:

• a luminance-defined transforming device, receiving a first luminance signal, a first chroma signal, and a second chroma signal so as to output a second luminance signal;
• a luminance shifting device, shifting said second luminance signal so as to output a luminance shifting signal;
• a luminance contrast adjusting device, adjusting said luminance shifting signal so as to output a luminance contrast adjusting signal;
• a black/white level extending device, receiving said luminance contrast adjusting signal so as to output a third luminance signal;
• and
• a luminance and color compensating device, compensating said first luminance signal, said first chroma signal, and said second chroma signal according to said second luminance signal and said third luminance signal.

A method for image contrast enhancement, comprising steps of:

• defining a second luminance signal according to a first luminance signal, a first chroma signal, a second chroma signal and at least a weighting signal;
• obtaining a third luminance signal by using a statistic histogram associated with said second luminance signal;
• and
• obtaining a fourth luminance signal by using a luminance curve graph according to said second luminance signal and said third luminance signal.

A method for image contrast enhancement, comprising steps of:

• defining a second luminance signal according to a first luminance signal, a first chroma signal, a second chroma signal and at least a weighting signal;
• shifting said second luminance signal so as to obtain a shifted signal;
• obtaining a third luminance signal by using a statistic histogram associated with said shifted signal;
• and
• obtaining a fourth luminance signal by using a luminance curve graph according to said shifted signal and said third luminance signal.